Apparatus for reducing the thickness of metal

ABSTRACT

A pendulum mill for reducing the thickness of metal and in which driving means to the pendulum arms are interconnected to eliminate backlash in the system.

[451 June 11,1974

United States Patent [191 Saxl m Q m m, w 9 U. G N I mi n E M mw S U Tmm R MC Pm AT Q 5 UNITED STATES PATENTS [75] Inventor:

Limited, Witton, Birmingham, England 1 Primary ExaminerLowe11 A. LarsonAttorney, Agent,

[22] Filed: Nov. 20, 1972 [21] Appl. No.: 307,825

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APPARATUS FOR REDUCING THE THICKNESS OF METAL BACKGROUND OF THEINVENTION ing the thickness of metal.

2. Description of the Prior Art In the specification of our British Pat.No. 889,662 there is described a method of reducing the thickness ofmetal which comprises advancing the metal between and beyond a pair offreely rotatable work-rolls disposed on opposite sides of the metal, andsubjecting the metal to the rolling action of the pair of workrolls, therolls moving in synchronism in pendulum-like manner at high speed andeffecting reduction in both directions of movement.

This method is performed by apparatus comprising a frame, a pair of armsoscillatable about pivotal axes, these arms having freely rotatableworkrolls mounted on their free ends which lie closer together thantheir pivotal axes, and mechanical driving means operable so as to causeoscillation of the arms in synchronism with one another. The mechanicaldriving means is provided by two crankshafts which are interconnected bya gear train, and one of the crankshafts is driven from an electricmotor. During use of the apparatus, the oscillating parts absorb energywhilst accelerating from a momentary stationary position at thebeginning of a stroke to full speed at approximately mid-point betweenthe ends of the travel of the workrolls. This energy is reabsorbed inthe rotating parts of the drive mechanism during travel between themid-point and the end of the stroke. Because of the different drives tothe two crankshafts, i.e. motor and drive shaft to one crankshaft, andgear train drive to the other crankshaft, it has been found that thedifference in the flywheel effect of the rotating parts connected to thetwo crankshafts disturbs the synchronisation of the oscillatable arms tothe extent permitted by the backlash in the gear train.

An object of the present invention is to provide an apparatus in whichthe above disadvantage is reduced.

SUMMARY OF THE INVENTION According to the present invention, apparatusfor reducing the thickness of metal comprises a frame, upper and loweroscillatable arms, each pivotally mounted about a pivotal axis upon theframe, the upper and lower arms having free ends which lie in closerrelationship than their pivotal axes, a freely rotatable workrollmounted on the free end of each arm and forming part of a workrollassembly, driving means associated with each arm for oscillating thearms in synchronism through a common plane in which the pivotal axes lieand for a distance on each side of the plane, each driving meansincluding an electric driving motor, the motors being connected-in anelectrical circuit whereby one provides a greater torque than the other,and a gear train connecting the driving means of one arm with thedriving means of the other arm at positions between the motors and thearms.

Preferably the gear train comprises a drive connecting shaft with gearsat each end for connecting the driving means of one arm with the drivingmeans of the other arm.

. posed of two half-shafts drivably connected together by means of acouplingwhichpermits relative angular adjustment of the half-shafts.

' With the one motor supplying greater torque than the other one, themotor supplying the greater torque places the drive connecting shaft intorque as the other motor tends to run at a slower speed. The torqueprovided by the drive connecting shaft tends to speed up the slowermoving driving means so that relative movement out of phase of the armsotherwise permitted by backlash is resisted.

ln one practical construction, the oscillating movement of the arms isimparted by connecting rods driven by crankshafts. To ensure that asmuch as possible of backlash and out of phase movement is eliminated, itis necessary to put the driving connecting shaft at the closest positionto the arms themselves. The most convenient position for the connectingshaft and gear train is, therefore, one in which it connects thecrankshafts together so as to maintain the rotational movement of thecrankshafts in phase.

It is preferable that in the electrical circuit, means are included forinfinitely varying the voltage to one of the motors relative to theother so as to vary the load placed by the drive connecting shaft andgears upon the driving means which would tend to run at a slower speed.

DESCRIPTION OF THE DRAWING One embodiment of the invention will now bedescribed by way of example only, with reference to the soleaccompanying drawing which is a side elevational view partly in sectionof apparatus forming the embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the embodiment, apparatus forreducing the thickness of metal consists of a rolling mill which isbasically of similar construction to apparatus for reducing metalthickness first described in the specification of our UK Pat. No.889,662.

The mill basically comprises a pair of pendulum arms 1 and 2, the upperarm 1 being pivotally mounted between spaced apart arm carrying beams 3about a pivotal axis 4 located intermediate the beam ends, and the lowerarm 2 being pivotally mounted in a similar manner between spaced apartarm carrying beams 3a. The beams are pivotally mounted to the mill frameby pivot pins 5 adjacent one end of each beam. The other end of eachbeam is free and is operably engaged by a screw-down load device 6. Atension spring 7 is provided to urge the two arms apart so as to holdthe upper beam 3 upwards when this is not subjected to a component ofrolling load and prevent it from dropping under its own weight. The twopivotal axes 4 of the two arms are disposed one directly above theother. A part of each arm extends from its pivotal axis towards theother arm to terminate in an end of the arm opposing that of the otherarm. Each of the opposing ends is provided with a workroll 8 freelyrotatably mounted thereon with its axis parallel to the pivotal axis 4of the arm and a plurality of supporting or back-up rolls 9 for theworkroll. The arms oscillate about their axes on both sides of apass-line A-A for metal to move the workrolls in synchronism alternatelyin the direction of 3 feed of the metal and then in the oppositedirection with the axes of the workrolls extending in a direction normalto the pass-line.

Driving means is provided for oscillating each arm 1, 2, through a planein which the pivotal axes 4 lie, the driving means comprising aconnecting rod pivotally mounted at one end to a part 11 of the arm onthe side of the pivotal axis 4 of the arm remote from its workroll 8.The other end of the connecting rod is pivotally mounted to aneccentric'crank portion 12 of a crankshaft 13. Each crankshaft isdrivably connected to a respective electric-driving motor 14 through anintermediate coupling (not'shown). The driving motors are connected inan electrical circuit whereby, in use, the motor'driving the upper arm 1is subjected to a greater voltage than the other motor so that itsupplies a greater torque than the other motor. I

.The end of each crankshaft l3 remote from its motor has keyed thereto abevelgear 15 which engages with a respective bevel gear 16 secured to anadjacent end of a connecting shaft 17. The shaft 17 is composed of twohalf shafts 17a, 17b drivably connected together by means of a coupling18 which permits fine angular adjustment to be made between the two halfshafts. The shaft 17 is thus connected to the upper and lowercrankshafts by means of the bevel gears and connects the driving meansof the upper arm 1 with the driving means of the lower arm 2 atpositions between the electric motors I4 and the arms.

in use of the apparatus, metal is fed towards and between the workrolls8 by feed rolls [9, the metal being reduced in thickness by theoscillating movement of the workrolls. By virtue of the arrangement thatthe motor which drives the upper arm 1 supplies a greater torque thanthe motor which drives the lower arm 2, and because the connecting shaft17 connects together the driving means for the upper and lower arms, theconnecting shaft is maintained in a state of torsion and eliminatesbacklash in the system between the crankshafts and the arms.Consequently, any variation in the static or dynamic forces acting onthe crankshafts is counteracted by the drive connecting shaft 17 and themovements of the upper and lower arms are maintained insynchronism.

In the above described construction, a means may be included forinfinitely varying the voltage supplied to one of the motors so that thepotential differential speeds of the two driving means may be infinitelyvaried. The torsional stresses in the drive connecting shaft may,therefore, be infinitely varied to suit any out of balance static ordynamic forces which may be set up in the apparatus so as tocounterbalance these forces and reduce or virtually eliminate any out ofphase rotation of the crankshafts and thereby improve synchronisation ofthe workrolls.

The alteration of the voltage upon one of the motors may be carried outmanually. Alternatively, an automatic control may be provided for thevoltage and this automatic control may be operated by a sensing devicemonitoring the actual relative position of the rollcarrying arms.

I claim:

1. Apparatus for reducing the thickness of metal comprising a frame,upper and lower oscillatable arms, each pivotally mounted about apivotal axis upon the frame, the upper and lower arms having free endswhich lie in closer relationship than their pivotal axes, a freelyrotatable workroll mounted on the free end of each arm and forming partof a workroll assembly, driving means associated with each arm foroscillating the arms in synchronism through a common plane in which thepivotal axes lie and for a distance on each side of the plane, eachdriving means including an electric driving motor, the motors beingconnected in an electrical circuit whereby one provides a greater torquethan the other, and a gear train connecting the driving means of one armwith the driving means of the other arm at positions between the motorsand the arms.

2. Apparatus according to claim 1 wherein the gear train comprises adrive connecting shaft with gears at each end for connecting the drivingmeans of one arm with the driving means of the other arm.

3. Apparatus according to claim 2 wherein the drive connecting shaft iscomposed of two half-shafts drivably connected together by means of acoupling which permits relative angular adjustment of the half-shafts.

4. Apparatus according to claim 1 wherein the driving means associatedwith each arm comprises a connecting rod driven by a crankshaft and thedrive connecting shaft and gear train connects the crankshafts together.

1. Apparatus for reducing the thickness of metal comprising a frame,upper and lower oscillatable arms, each pivotally mounted about apivotal axis upon the frame, the upper and lower arms having free endswhich lie in closer relationship than their pivotal axes, a freelyrotatable workroll mounted on the free end of each arm and forming partof a workroll assembly, driving means associated with each arm foroscillating the arms in synchronism through a common plane in which thepivotal axes lie and for a distance on each side of the plane, eachdriving means including an electric driving motor, the motors beingconnected in an electrical circuit whereby one provides a greater torquethan the other, and a gear train connecting the driving means of one armwith the driving means of the other arm at positions between the motorsand the arms.
 2. Apparatus according to claim 1 wherein the gear traincomprises a drive connecting shaft with gears at each end for connectingthe driving means of one arm with the driving means of the other arm. 3.Apparatus according to claim 2 wherein the drive connecting shaft iscomposed of two half-shafts drivably connected together by means of acoupling which permits relative angular adjustment of the half-shafts.4. Apparatus according to claim 1 wherein the driving means associatedwith each arm comprises a connecting rod driven by a crankshaft and thedrive connecting shaft and gear train connects the crankshafts together.